:root {
  --primary: #2563eb;
  --accent: #22c55e;
  --text: #0f172a;
  --muted: #64748b;
  --bg: #f8fafc;
  --border: #e2e8f0;
  --error: #ef4444;
  --success: #10b981;
  --warning: #f59e0b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Inter', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

.container {
  max-width: 600px;
  margin: 48px auto;
  padding: 32px;
  background: #fff;
  border-radius: 16px;
  box-shadow: 0 20px 40px rgba(15, 23, 42, 0.08);
}

h1 {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 32px;
  color: var(--text);
}

/* Form Styles */
.form-group {
  margin-bottom: 24px;
}

label {
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 8px;
  display: block;
  color: var(--text);
}

.help-text {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 6px;
  display: block;
  line-height: 1.4;
}

input {
  width: 100%;
  padding: 14px 16px;
  font-size: 1rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  transition: border 0.2s ease, box-shadow 0.2s ease;
  margin-top: 4px;
}

input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

input.error {
  border-color: var(--error);
}

/* Buttons */
.form-actions {
  display: flex;
  gap: 12px;
  margin-top: 32px;
  flex-wrap: wrap;
}

button {
  flex: 1;
  min-width: 140px;
  padding: 14px 24px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--primary), #1d4ed8);
  color: #fff;
  border: none;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

button:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

.secondary-btn {
  background: #f1f5f9;
  color: var(--text);
}

.secondary-btn:hover {
  background: #e2e8f0;
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.15);
}

/* Error Message */
.error-msg {
  margin-top: 20px;
}

.error-box {
  background: #fee;
  border-left: 4px solid var(--error);
  padding: 16px;
  border-radius: 8px;
  color: #b91c1c;
  margin-top: 12px;
}

/* Results Section */
.result {
  margin-top: 32px;
  padding: 24px;
  background: linear-gradient(135deg, #f0fdf4, #dcfce7);
  border-radius: 16px;
  border-left: 6px solid var(--success);
}

.result h3 {
  margin: 0 0 20px 0;
  color: var(--text);
  font-size: 1.5rem;
}

.result p {
  margin: 12px 0;
  font-size: 1.1rem;
}

.result strong {
  color: var(--text);
  font-weight: 600;
}

.highlight-amount {
  background: white;
  padding: 20px;
  border-radius: 12px;
  margin: 16px 0;
  border: 2px solid var(--success);
}

.highlight-amount p {
  margin: 8px 0;
  font-size: 1.15rem;
}

/* Chart */
canvas {
  display: block;
  max-width: 600px;
  height: 350px;
  margin: 32px auto;
  border-radius: 12px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
}

/* Table */
.table-wrapper {
  overflow-x: auto;
  margin-top: 32px;
  border-radius: 12px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

table {
  width: 100%;
  border-collapse: collapse;
  background: white;
}

thead {
  background: var(--primary);
  color: white;
}

th,
td {
  padding: 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.85rem;
  letter-spacing: 0.5px;
}

td:first-child {
  font-weight: 600;
}

tbody tr:nth-child(even) {
  background: #f8fafc;
}

tbody tr:hover {
  background: #eff6ff;
}

tbody tr:last-child td {
  font-weight: 600;
  background: #dbeafe;
  border-bottom: none;
}

/* Content Section */
.content-section {
  margin-top: 48px;
  padding: 32px;
  background: #f8fafc;
  border-radius: 16px;
  border-left: 6px solid var(--primary);
}

.content-section h2 {
  color: var(--text);
  margin-top: 0;
}

.content-section h2:first-child {
  margin-top: 0;
}

.content-section h3 {
  color: var(--text);
  margin-top: 32px;
  font-size: 1.3rem;
}

.content-section h4 {
  color: var(--text);
  margin-top: 24px;
  font-size: 1.1rem;
}

.content-section p,
.content-section li {
  line-height: 1.8;
  color: var(--text);
}

.content-section ul,
.content-section ol {
  padding-left: 24px;
}

.content-section li {
  margin-bottom: 8px;
}

.content-section a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 600;
}

.content-section a:hover {
  text-decoration: underline;
}

.formula-box {
  background: #faf5ff;
  border-left: 4px solid #a855f7;
  padding: 20px;
  border-radius: 8px;
  margin: 20px 0;
  font-family: 'Courier New', monospace;
}

.formula-box strong {
  font-size: 1.1rem;
  display: block;
  margin-bottom: 12px;
}

/* Note */
.note {
  margin-top: 32px;
  padding: 20px;
  background: #fef3c7;
  border-left: 4px solid var(--warning);
  border-radius: 8px;
  font-size: 0.95rem;
}

/* Ads Placeholder */
.ads {
  margin: 32px 0;
  padding: 16px;
  background: #f1f5f9;
  border: 1px dashed var(--border);
  text-align: center;
  font-size: 0.9rem;
  color: var(--muted);
  border-radius: 12px;
}

/* Breadcrumb */
.breadcrumb {
  margin-bottom: 24px;
  font-size: 0.9rem;
  color: var(--muted);
}

.breadcrumb a {
  color: var(--primary);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

.breadcrumb span {
  margin: 0 8px;
}

.breadcrumb .current {
  color: var(--text);
  font-weight: 600;
}

/* Print Styles */
@media print {
  body {
    background: white;
  }

  .container {
    box-shadow: none;
    max-width: 100%;
  }

  .navbar,
  .ads,
  button,
  .form-actions {
    display: none;
  }

  canvas {
    max-width: 100%;
    page-break-inside: avoid;
  }

  .result {
    page-break-inside: avoid;
  }

  table {
    page-break-inside: auto;
  }

  tr {
    page-break-inside: avoid;
  }
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    margin: 24px 16px;
    padding: 24px;
  }

  h1 {
    font-size: 1.6rem;
  }

  .form-actions {
    flex-direction: column;
  }

  button {
    width: 100%;
  }

  canvas {
    height: 280px;
  }

  table {
    font-size: 0.9rem;
  }

  th,
  td {
    padding: 12px 8px;
  }

  .content-section {
    padding: 20px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 20px;
  }

  h1 {
    font-size: 1.4rem;
  }

  input {
    padding: 12px;
    font-size: 0.95rem;
  }

  .result {
    padding: 16px;
  }

  .result h3 {
    font-size: 1.2rem;
  }

  .result p {
    font-size: 1rem;
  }

  canvas {
    height: 240px;
  }

  table {
    font-size: 0.85rem;
  }

  th,
  td {
    padding: 10px 6px;
  }
}

.related-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.related-links a {
  background: white;
  padding: 12px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--primary);
  font-weight: 600;
  font-size: 0.9rem;
  border: 1px solid var(--border);
  transition: all 0.2s ease;
  display: block;
  text-align: center;
}

.related-links a:hover {
  border-color: var(--primary);
  background: #eff6ff;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
  text-decoration: none;
}

/* Back to Top Button */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  z-index: 9999;
}

.back-to-top a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 50px;
  height: 50px;
  background: #2563eb;
  color: white;
  text-decoration: none;
  border-radius: 50%;
  font-size: 24px;
  font-weight: bold;
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
  transition: all 0.3s ease;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}

.back-to-top a:hover {
  background: #1d4ed8;
  transform: translateY(-4px);
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.4);
}

@media (max-width: 768px) {
  .back-to-top {
    bottom: 20px;
    right: 20px;
  }
  
  .back-to-top a {
    width: 48px;
    height: 48px;
    font-size: 22px;
  }
}